As a follow-up, I took a look at the costs for the DCMS Combat Commands (both regular & the "reinforced" ones like the Swords of Light regiments):
-- House Kurita shows them having 66 "House" Combat Commands, with 9 "Questionable" (1 Green, 4 Regular, & 4 Veteran), 49 "Reliable" (18 Green, 18 Regular, 12 Veteran, & 1 Elite), & 8 "Fanatical" (2 Green, 1 Regular, 2 Veteran, & 3 Elite).
-- The "default" (assuming x1.0 multipliers) is that you will get a Green/Reliable Combat Command (138 RP for regular, 150 for a reinforced); starting off at Regular doubles the cost, but going down to "Really Green" cuts 25% off, while "Wet Behind the Ears" is half cost
-- Supply is only dependent on if the unit is in combat or not (12 or 49 RP for regulars, 13 or 53 RP for reinforced), whether you're Super Green or Elite as all get-out.
-- Elevating a unit from Questionable to Reliable costs half the normal RP to purchase the same unit outright; elevating it from Questionable to Fanatical costs the same as a brand-new unit.
-- Assuming non-combat support for the beginning units, & based on the faction's starting RP, the leftover RP is enough to elevate the 9 Questionable Combat Commands to Reliable after 4 turns...assuming zero combat by any DCMS units. Elevating the 48 non-Elite Reliable units to Fanatical would take another 18 turns (again, no combat whatsoever). Elevating all 57 units to Fanatical status would take 26 turns, again with no combat.
-- Based on those costs, I could maybe see elevating the Questionable units...but otherwise, it's a lot more cost-effective to spend the RP on new units (or even on manufacturing). Those 4 turns, for example, could have seen you add 12 additional Green/Questionable Combat Commands (or increasing your combat forces by about 15%).
So, improving your reliability rating is not going to come cheap.